The LCD (Liquid Crystal Display) possesses many advantages of being ultra thin, power saved and radiation free. It has been widely utilized in, such as LCDTV, mobile phones, Personal Digital Assistant (PDAs), digital cameras, laptop screens or notebook screens.
Generally, the liquid crystal display comprises a shell, a LCD panel located in the shell and a backlight module located in the shell. Particularly, the structure of the liquid crystal panel mainly comprise a Thin Film Transistor Array Substrate (TFT Array Substrate), a Color Filter Substrate (CF Substrate) and a Liquid Crystal Layer. The working principle is that the light of backlight module is reflected to generate images by applying driving voltages to the two glass substrate for controlling the rotations of the liquid crystal molecules.
Please refer from FIG. 1 to FIG. 2, which shows diagrams while the liquid crystal panels of prior arts are in the curve state. The liquid crystal panel comprises a CF substrate 100, a TFT substrate 200 and a liquid crystal layer 300 between the CF substrate 100 and the TFT substrate 200. The CF substrate 100 comprises a first substrate 110, a color resist layer 120 and a black matrix (BM) 130 located on the first substrate 110. The TFT substrate 200 comprises a second substrate 200, a shielding line 220 and a data line 230. In normal condition, the black matrix 130 can cover the gap between the shielding line 220 and the data line 230 to prevent the light leakage. When the liquid crystal panel is applied for curve display, because of the curvature radius difference of the TFT substrate 200 and the CF substrate 100, the relative position shift occurs between the black matrix 130 on the CF substrate 100 and the film layers on the TFT substrate 200. Thus, the light leakage happens on the curved liquid crystal panel, and in the meantime, a part of the aperture ratio will be lost.
For raising the aperture ratio of the liquid crystal panel and reducing the production costs, people propose a Color filter On Array (COA) technology, in which the RGB color resists at the CF substrate side is transferred to be manufactured on the array substrate, and the previous substrate merely preserves the black matrix, the common electrode and the Photo Spacer (PS).
Please refer from FIG. 3 to FIG. 4, which show the sectional structure diagrams of the COA liquid crystal panel according to prior art. The color resist layer 250′ is located on the lower substrate 200′. As shown in FIG. 3, the black matrix 130′ of the upper substrate 100′ completely covers the gap between the data line 240′ and the shielding line 220′, and meanwhile extra covers a portion of the shielding line 220′. The range of the shielding line 220′ which is extra covered by the black matrix 130′ in the horizontal direction is 1-2 μm, which is specifically to be 1.35 μm in the COA liquid crystal panel in FIG. 3. The light leakage issue due to the exposure of the gap caused by alignment shift of the upper, lower substrates 100′, 200′ can be prevented. However, once the COA liquid crystal panel is applied for curve display, the misalignment distance of the black matrix 130′ will become larger than the range which is previously shielded by the black matrix 130′, and there still might be chances to cause the light leakage happen. Thus, as shown in FIG. 4, the improvement is required for the COA liquid crystal panel in FIG. 3, to increase the range of the shielding line 220′ shielded by the black matrix 130′ up to 6-7 μm, which is specifically to be 7 μm in the COA liquid crystal panel in FIG. 4. Although this can prevent the light leakage happening, it will result in the decrease of the aperture ratio.
For preventing the light leakage while the liquid crystal panel is applied for curve display and ensuring the aperture ratio of the liquid crystal panel in the mean time, people propose a BM On Array (BOA) technology, which is also to manufacture the black matrix on the array substrate. Thereby, the bad influences of light leakage, interference brought by the panel bending which the present curve liquid crystal panel faces can be solved. Meanwhile, the aperture ratio of the liquid crystal panel can be ensured.
Please refer to FIG. 5, which is a sectional structure diagram of a BOA liquid crystal panel according to prior art. Both the color resist layer 250″ and the black matrix 260″ are located on the lower substrate 200″. Only the common electrode 120″ remains on the upper substrate 100″.The black matrix 260″ completely covers the gap between the data line 240″ and the shielding line 220″. Because the maximum alignment shift of the exposure apparatus itself is 3 μm, the black matrix 260″ should cover at least 3 μm range of the shielding line 220″ for preventing the exposure of the gap between the data line 240″ and the shielding line 220″. Besides, for avoiding the risk of generating the fringes due to the liquid crystal tilt inside the pixel caused by the uneven appearance because of the shift of the black matrix 260″, the spaced distance between the black matrix 260″ and the pixel electrode 270″ is 3 μm, and meanwhile, the range of the shielding line 220″ covered by the pixel electrode 270″ in the horizontal direction is 2 μm. In sum, the width of the shielding line 220″ is 8 μm. The aperture ratio is saved in comparison with a normal COA liquid crystal panel.
Nevertheless, the width of the shielding line 220″ in the BOA liquid crystal panel shown in FIG. 5 is larger, which must influence the aperture ratio to a certain extent. Therefore, there is a need to provide a new BOA liquid crystal panel for raising the aperture ratio of the liquid crystal panel in advance.